Accuracy Check - Hach POCKET COLORIMETER II Instruction Manual

Accuracy Check

Standard Additions Method
1. Use a TenSette
1000 mg/L SiO
70 mg/L SiO
2
2. Analyze each sample as described in the procedure. The silica concentration
should increase 10 mg/L for each 0.1 mL of standard added.
3. If these increases do not occur, an interfering substance is likely present. See
Interferences on page 1—22
more information on standard additions.
Standard Solutions Method
To check the accuracy of the method, use a Silica Standard Solution, 10, 25, or
50 mg/L SiO , see
2
in place of the sample in the procedure using deionized water as the blank.
®
Pipet to add 0.1, 0.2, and 0.3 mL of Silica Standard Solution,
, to three 10-mL portions of a sample containing less than
2
. Cap the sample cells and invert to mix.
or consult the Hach Water Analysis Handbook for
Optional Reagents on page 1—24. Analyze the standard solution
1—21
Silica, HR,
continued